Excessive use of form lines should be avoided as this will complicate the map and give a wrong impression of height differences. If the representation of an area needs a large number of form lines, a smaller contour interval provides a more legible alternative.

The relative height difference between neighbouring features must be represented on the map as accurately as possible. Absolute height accuracy is of less importance. It is permissible to alter the height of a contour slightly if this will improve the representation of a feature. This deviation should not normally exceed 25% of the contour interval and attention must be paid to neighbouring features.

	101 Contour A line joining points of equal height. The standard vertical interval between contours is 5 metres. Colour: brown. 102 Index contour Every fifth contour should be drawn with a thicker line. This is an aid to the quick assessment of height difference and the overall shape of the ground. Where one of these contours coincides with an area of small knolls or depressions, it may be shown with a normal contour line. Colour: brown. 103 Form line An intermediate contour line. Form lines are used where more information can be given about the shape of the ground. They are used only where representation is not possible with ordinary contours. Only one form line may be used between neighbouring contours. Colour: brown.
	104 Slope line Slope lines may be drawn on the lower side of a contour line, eg along the line of a re-entrant or in a depression. They are used only where it is necessary to clarify the fall of the ground. Colour: brown.
	105 Contour value Contour values are often included to aid assessment of large height differences. They are inserted in the index contours in positions where other detail is not obscured. The figures should be orientated so that the top of the figure is on the higher side of the contour. Colour: brown.
	106 Earth bank A steep earth bank is an abrupt change in ground level which can be clearly distinguished from its surroundings, e.g. gravel or sand pits, road and railway cuttings or embankments.The tags should show the full extent of the slope, but may be omitted if two banks are close together. Impassable banks should be drawn with symbol 201 (impassable cliff). Colour: brown.
	107 Earth wall Distinct earth wall. Colour: brown.
	108 Small earth wall A partly ruined earth wall may be shown with a dashed line. Colour: brown.
	109 Erosion gully An erosion gully or trench which is too small to be shown by symbol 106 is shown by a single line. The line width reflects the size of the gully. Minimum depth 1m. The end of the line is pointed. Colour: brown.
	110 Small erosion gully A small erosion gully or trench. Minimum depth 0.5 m. Colour: brown.
	111 Knoll Knolls are shown with contour lines. A prominent knoll falling between contour lines may still be represented by a contour line if the deviation from the actual contour level is less than 25%. Smaller or flatter knolls should be shown with form lines. Colour: brown.
	112 Small knoll A small obvious mound or rocky knoll which cannot be drawn to scale with a contour (diameter of mound less than ca. 5 m). Knolls of any other shape than round should be shown by contours. The height of the knoll should be a minimum of 1m from the surrounding ground. Colour: brown.
	113 Depression Depressions are shown with contours or form lines and slope lines. Prominent depressions falling between contour lines may be represented by a contour line if the deviation from the actual contour level is less than 25%. Smaller or shallower depressions should be shown by form lines. Colour: brown.
	114 Small depression Small shallow natural depressions and hollows (minimum diameter 2m) which cannot be shown to scale by contours are represented by a semicircle. Minimum depth from the surrounding ground should be 1m. Location is the centre of gravity of the symbol, which is orientated to north. Symbol 115 is used for manmade pits. Colour: brown.
	115 Pit Pits and holes with distinct steep sides which cannot be shown to scale by symbol 106 (minimum diameter 2m). Pits with any other shape than round should be shown by contours. Minimum depth from the surrounding ground should be 1m. Location is the centre of gravity of the symbol which is orientated to north. Colour: brown.
	116 Broken ground An area of pits or knolls which is too intricate to be shown in detail. The density of dots may vary according to the detail on the ground. Colour: brown.
	117 Special landform feature This symbol can be used for a special small landform feature. The definition of the symbol must be given in the map legend. Colour: brown.
	118 Spot height Spot heights are used for the rough assessment of height differences. The height is given to the nearest metre. The figures are orientated to the north. Water levels are given without the dot. Colour: black.